The biochemical analyzer is a commonly used instrument for clinical diagnosis, which determines various biochemical data, such as hemoglobin, cholesterol, and creatinine, by analyzing serum and/or other body fluids. The biochemical analyzer takes the measurements based on the Lambert-Beer's law which measures how much of the incident light of a certain wavelength range is absorbed by a solution, i.e., absorbance of that solution, to finally determine its concentration upon various calculations.
The monochromatic light used in the measurements may be obtained by means of various monochromators, for example, a diffraction grating or prism, or an interference filter.
Typically, the grating may not be applicable to a small-sized biochemical analyzer because it may be expensive and thus makes it difficult to reduce the size of the instrument due to the use of the grating. The interference filter may be classified into an interference filter operated in a static mode and/or an interference filter operated in a dynamic mode.
In a static mode, each filter corresponds to one of the monochromatic measuring channels, and each has its own photoelectric processing unit. The plurality of channels takes measurements simultaneously. Although the static mode is advantageous in term of speed, the advantages are often compromised due to the higher cost, and thus the interference filter working at the static mode may not be applicable to small-sized or reduced-sized biochemical analyzers.
In a dynamic mode monochromators typically comprise filters arranged in a wheel structure. In a system that employs a monochromator having the filters arranged in a wheel pattern, each monochromatic light path shares a photoelectric sampling and processing system and may thus reduce the cost and gaining popularity in small-sized or reduced-sized biochemical systems and other photometric colorimetric systems. The filter wheel structure may also be implemented in various manners. For examples, the filters may have their surfaces either perpendicular to or parallel with the central axis about which the wheel rotates. The parallel configuration may be less widely adopted in the optical systems because it tends to occupy a larger space, and the measurement accuracy may be adversely affected by the angle of the incident light beams. Hence, the perpendicular configuration is more widely used in the art.
For small- or reduced-sized, automatic biochemical analyzers, it may be even more difficult to obtain a precise, reliable, efficient while simple measurement. Hence, due consideration should be given to whether the analyzer supports a dual-wavelength measurement because the dual-wavelength measurement may be applicable to various test items and may efficiently remove some interferences and thus make a significant contribution to a reliable and efficient measurement.
Currently, some of the small- or reduced-sized automatic biochemical analyzers use filter wheels as their monochromatic light splitting elements. Specifically, a reaction tray rotates in a uniform manner for each cycle, and transfers a constant number of reaction cuvettes sequentially to a photoelectric measurement position. When the reaction tray halts at a certain position, the filter wheel causes a filter that allows a light of a certain wavelength which is specific to the solution in the reaction cuvette to halt at the photoelectric measurement position, and measures the colorimetric absorbance with respect to the light components of that wavelength. Although this method may guarantee the consistency of the measurements, its implementation is rather complicated as it requires halting a corresponding filter at the photoelectric measurement position based on the wavelength that is specific to the solution in each of the reaction cuvette. When the measurement with respect to the current reaction cuvettes is completed, the next reaction cuvette will be transferred or rotated to the measuring position. In these systems, no measurement may be taken until or unless the reaction cuvettes and the filter come to a halt.
Moreover, each time when a reaction cuvette halts and/or restarts, it results in some vibration. This may explain why no data are generally sampled until a period of time lapses such that the vibration may be reduced to a certain extent to avoid unreliable measurement results. Similarly, each time when the filter wheel rotates to a desired wavelength or halts, data are generally sampled when a certain period of time lapses such that the vibration may be reduced to an allowable level. As a result, a much longer time period may be needed for measuring the solutions in the reaction cuvettes. What may further worsen the situation is that, in the case of a dual-wavelength measurement, each time when a reaction cuvette halls the filter wheel may be required to completely halt at filters of two wavelengths to sample data so even a longer time period may be demanded. Additionally, because a different number of reaction cuvettes may demand the dual-wavelength measurement for each cycle, this may result in non-uniform time intervals between sampling points which may be disadvantageous in terms of repeatability and reliability of the measurements. As is hereinabove described, such a method may require transferring a plurality of reaction cuvettes, one by one, to the optical axis for photoelectric data measurement. In order to save time and to ensure uniform time intervals between sampling points, the implementation may be concerned with performing a dual-wavelength measurement on the first and last reaction cuvettes only. In other words, in the cases where data concerning the intermediate procedures are to he sampled, the filter wheel structure as characterized above may not support the dual-wavelength test.
The US patent application publication US 2003/072680 develops a photoelectric measuring method different from those that have been described above. In that application, the filter wheel rotates uniformly and measurements are taken when the reaction tray halts. In this way, that approach effectively removes the unfavorable effects on the measurement due to vibration caused by the start and/or stop of the filter wheel. Meanwhile, because the filter wheel may be in a uniform rotation, when a reaction cuvette stops, it may be allowable to complete absorbance measurements at all wavelengths within a relatively short period of time.
Thus, any test item may be subjected to a dual-wavelength measurement. On the other hand, this patent application publication also discloses that like the other existing techniques, data can also be sampled only when the vibration caused by the start or stop of the reaction tray fades away. Thus, a huge amount of time is similarly demanded for sampling data for each solution in the reaction cuvettes.
In addition, according to the patent application publication, the reaction tray rotates in a fixed manner during each cycle, and the number of cuvettes transferred to the measuring position in each cycle is equal to the total number of the reaction cuvettes in one cycle plus one or minus one. Thus, the reaction tray traverses in a clockwise or counterclockwise direction and stops at a next cuvette position every cycle. The photoelectric sampling is performed on a fixed number of continuous reaction cuvettes every cycle. The longest reaction time (i.e., the time required for continuous monitoring the same item) supported by the instrument directly depends on the number of the reaction cuvettes involved in the photoelectric sampling every cycle and the length of the working cycle.
For example, if the working cycle of the instrument is 20 seconds, and a total of 24 reaction cuvettes are involved in the measurements, then the longest continuous monitoring time period supported by the instrument will be 20*24=480 seconds, i.e., 8 minutes. However, the working cycle of the instrument is directly associated with the measurement speed so this time period should not be unduly long. In the case of a clinic test, the allowable longest continuous monitoring time period may be about 10 minutes in general. Apparently, the measurement speed as described in the aforementioned patent application publication has not been improved enough to address the needs of clinic tests.